Garments to provide protection from the weather have been available for many years. Early garments were made using water impermeable materials (e.g. rubber-coated textiles) which were cut and sewn into garments. The seams were then sealed with polymers to preclude leakage of moisture inward to the wearer. These garments provided the desired weather protection but were not comfortable. In particular, they were heavy and prevented dissipation of body moisture transpired by the wearer (non breathable garment). Attempts were made to address the lack of breathability by incorporating vents under the arms and/or along the upper back to enable perspiration vapor to escape. To retain the water impermeability, however, more fabric was added to these vents in the form of a rain shield or drape to preclude rain or water coming into the vent holes. This significantly reduced the venting action and made the garment heavier.
Next, to address the weight issue, lighter weight and lower cost materials were used (e.g. polyvinyl chloride) with same or similar garment design. The seams were made by continuous heat bonding the cut pieces of material together to provide the water impermeable seams. However, these lighter weight and lower cost protective garments were still not comfortable due to their inability to adequately vent the wearer""s body-transpired moisture.
When breathable materials were invented, such as GoreTex(copyright), new garments were made using these fabrics. Since supporting,textiles are used to provide strength to the breathable film, special sewn seams are needed to preclude inward leakage. Both the breathable fabric and the seams, which require hand work, raise the cost of manufacturing of such garments. The lower cost continuous heat bonding method used to make seams on the less expensive vinyl garments do not work on the laminated breathable films due to puckering, burn-through or lack of penetration caused by the inability to heat-fuse dissimilar materials. Consequently, although these weather protective garments are lighter in weight than the early rubber-coated textile garments and are breathable, they are also very expensive. While a lightweight, non breathable vinyl jacket might cost about five dollars, a comparable jacket made from a fabric-backed breathable film might cost about one hundred dollars.
Accordingly there remains a need for inexpensive, lightweight, breathable protective outer garments.
It has now been discovered that a lightweight, breathable protective outer garment can be made at a low cost. This is attained by using certain breathable laminated fabrics and discontinuous sonic bonding to create an acceptable weather resistant seam with adequate strength. The new seaming technique permits a different garment pattern, both of which in combination result in a much lower cost garment assembly using the lightest weight breathable laminate available. Examples of such garments include ponchos, parkas, jackets and pants.
Hence in one aspect, the invention resides in a weather-protective outer garment, such as a rain parka or poncho, consisting essentially of a breathable laminated fabric comprising a polyolefin nonwoven fabric discontinuously bonded to a foraminous polyolefin film with an adhesive, such as a water-based or polyurethane adhesive, said laminated fabric oriented such that the polyolefin film side of the fabric is the outward-facing surface of the garment, said garment having one or more discontinuously ultrasonically bonded seams in which the polyolefin film sides of two laminated fabric edges are melted together, said seam(s) having a strength of about 2000 grams per inch of seam width or greater, and said laminated fabric having a basis weight of about 80 grams per square meter or less, a hydrohead of about 50 centimeters or greater, and a breathability of about 1000 grams per square meter per 24 hours or greater.
Suitable laminated fabrics include those disclosed in copending application Ser. No. 08/680,890 filed Jul. 16, 1996 entitled xe2x80x9cProcess of Manufacturing a Water-Based Adhesive Bonded, Sovent Resistant Protective Laminatexe2x80x9d (F. G. Druecke et al.), which is hereby incorporated by reference. Other suitable laminated fabrics include any breathable, ultrasonically bondable laminate having a hydrohead of about 50 centimeters or greater.
As used herein, xe2x80x9cseam strengthxe2x80x9d is determined by a standard test for Peel Resistance of Adhesives (T-Peel Test) in accordance with ASTM D 1876-72 (reapproved 1983). The seams in the garments of this invention can have a seam strength of from about 2000 grams per inch of seam width or greater, more specifically from about 2000 to about 7000 grams per inch, and still more specifically from about 2500 to about 3000 grams per inch.
As used herein, xe2x80x9chydroheadxe2x80x9d is a measure of a material""s resistance to liquid penetration as determined in accordance with the standard hydrostatic pressure test AATCCTM No. 127-1977. The hydrohead of the laminated fabric used to construct the garments of this invention can be about 50 centimeters or greater, more specifically from about 100 to about 200 centimeters, and still more specifically from about 100 to about 150 centimeters.
As used herein, the xe2x80x9cbreathabilityxe2x80x9d for the materials useful for purposes of this invention is the water vapor transmission rate (WVTR) calculated in accordance with ASTM Standard E96-80. Circular samples measuring three inches in diameter are cut from each of the test materials and a control which is a piece of CELGUARD(copyright) 2500 film from Hoechst Celanese Corporation of Sommerville, New Jersey. CELGUARDO(copyright) 2500 film is a microporous polypropylene film. Five samples are prepared for each material. The test dish is a number 60-1 Vapometer pan distributed by Thwing-Albert Instrument Company of Philadelphia, Pa. One hundred millimeters of water are poured into each Vapometer pan and individual samples of the test materials and control material are placed across the open tops of the individual pans. Screw-on flanges are tightened to form a seal along the edges of the pan, leaving the associated test material or control material exposed to the ambient atmosphere over a 6.5 centimeter diameter circle having an exposed area of approximately 33.17 square centimeters. The pans are placed in a forced air oven at 100xc2x0 F. (32xc2x0 C.) for 1 hour to equilibrate. The oven is a constant temperature oven with external air circulating through it to prevent water vapor accumulation inside. A suitable forced air oven is, for example, a Blue M Power-O-Matic 60 oven distributed by Blue M Electric Company of Blue Island, Ill. Upon completion of the equilibration, the pans are removed from the oven, weighed and immediately returned to the oven. After 24 hours, the pans are removed from the oven and weighed again. The preliminary test water vapor transmission rate values are calculated as follows:
Test WVTR=(grams weight loss over 24 hours)xc3x97315.5 g/m2/24 hrs
The relative humidity within the oven was not specifically controlled.
Under predetermined set conditions of 100xc2x0 F. (32xc2x0 C.) and ambient relative humidity, the WVTR for the CELGUARD(copyright) 2500 control has been determined to be 5000 grams per square meter for 24 hours. Accordingly, the control sample is run with each test and the preliminary test values are corrected to set conditions using the following equation:
WVTR=(Test WVTR/control WVTR)xc3x975000 g/m2/24 hrs) (g/m2/24 hrs).
The breathability of the laminated fabric used to construct the garments of this invention can be about 1000 grams per square meter per 24 hours or greater, more specifically from about 1000 to about 4000 grams per square meter per 24 hours, and still more specifically from about 2500 to about 3500 grams per square meter per 24 hours.
In addition to being lightweight and effective garments, the cost of making the garments of this invention is very low due to the low basis weight of the laminated fabric and the ultrasonic seaming method. As a result of the relatively low manufacturing costs, the wholesale price of these garments (the price charged by the manufacturer to a distributor or retailer) can be, in 1997 U.S. dollars, about 20 dollars or less, more specifically about 10 dollars or less, and still more specifically from about 2 to about 8 dollars, depending on the style of the garment and the amount of fabric used. In any given year, the wholesale price in 1997 dollars can be readily determined by adjusting the then-current wholesale price using the change in the Consumer Price Index.